Preheat oven broiler. Place tomatillo halves, skin sides up, and serrano chili in a baking dish and broil 7 to 10 minutes until well browned. Remove and cool.

Mash avocados in a large bowl with lime juice. Add garlic, scallions and cilantro. Remove any blackened skin from tomatillos, chop them and add to the avocado mixture. Seed roasted serrano chili, chop and add to salsa. Season with salt. Makes 4 to 6 servings.